whew! I just got off the phone with tech support and found the answer. Although I have a macos Sierra 10.12.3 and Camtasia 3.0.4, apparently the mac Air does not download nicely with camtasia with a 1.4 GHz core and 4 GB memory. So, I am using my windows computer now.

with the size and complexity of Applications your lucky if you can get by on 8 GB memory. My recently purchased MacBook pro has 16 GB and I would feel more comfortable 32 I also have a 1TB SSD. About all a 4 GB machine will do is surf the internet with today's apps.